BMB 6

Question 1

What two processes in the brain maintain adequate bloodflow?

Answer 1

1) autoregulation

2) local metabolites like co2

Question 2

urgent vs emergency HTN? in terms of sx and tx?

Answer 2

both are 180/120 mm hg, diff is that emergent has acute end organ damage such as brain swelling/bleeding and fluid in lungs or aortic dissection/MI
-tx: for urgent, immediate with oral meds, usu no hospitalization, but emergent has hospitalization in ICU and IV meds

Question 3

What is the critical range of blood pressure in which autoregulatory (vasculature maintanence of constant blood flow) mechanisms work?

Answer 3

50-150mm hg, plateau on graph of CBF
If bp too high, arterioles vasconstrict to reduce blood flow, but if hypotnesive, then dilate (but in extreme HTN, presssure is higher than autoreg range so arterioles end up vasodilating and “breaking through” plateau)

Question 4

How does an increase vs decrease on CO2 modify autoregulation?

Answer 4

INcrease in CO2 (hypercapnia) shifts curve up and left to get rid of CO2 (so CBF increases, vasodilation) to get rid of co2. Reduced autoregulatory range, breakthrough point occurs sooner/at lower pressures

-decrease in CO2 means curve goes down and right with incr autoreg range, produces vasocon to hold onto co2

Question 5

How does mean arterial BP affect autoreg?

Answer 5

in HTN (incr in MAP), CBF is generally decreased because the lumen diameter is decr

Question 6

What happens to autoreg mechs after stroke?

Answer 6

Impaired!, blood flow pressure passive, myogenic sys dmged, METABOLISM DRIVES CBF
-focal metabolic coupling: all major metabolites are vasodilators, blood flow will oversupply these and o2 after stroke then release will go back to normal

Question 7

How do glial cells affect local brain blood flow?

Answer 7

• glial cells are around vessels/capillaries, regulate EC K+ (by taking it up and resdistributing it to other areas) thus protect cell from depol so prevent it from being hyper excitable aka causing seizures (also take up glutamate and convert it)
• they can also swell by taking up excess fluid via aquaporins to protect neurons from swelling

Question 8

What is and isnt the major regulatory molecule to regulate CBF?

Answer 8

CO2 is, O2 is not unless in severe hypoxia (diff from periph circ/chemorec that do respond to O2)

Question 9

In which pop is decr in cerebral met and decr in blood flow most likely to occur?

Answer 9

loss of neurons in elderly w atherosclerosis, >25

Question 10

What 2 features of EEG are we most interested in?

Answer 10

amp and freq

Question 11

What does amp in eeg depend on (2 factors

Answer 11

number of active elements (action/syn potls) and synchrony (incr amp)

Question 12

Why are synaptic potentials more impt than ap (and greater contributor to EEG spikes and waves?)

Answer 12

glial cells, slower and better picked up by EEG

EEG has small amp with greater distance traveled

Question 13

which bands of waves are teh slowest? which are seen in the HC? whcih are made with eyes closed and slow? which rep awake activity

Answer 13

delta- slowest, deep sleep, lowest freq
theta-seen in HC
alpha- eyes closed/drowsy, more regular
beta- mixed is awake, high freq

Question 14

Evoked potential–what is the purpose of it/what does it test

Answer 14

reflect stimulation and tests sensory pathway in patient eg who is comatose, used often in the SC bc more sensitive than MRI, also assess vis/aud pathways in kids

Question 15

Epilepsy def

Answer 15

seizures that occur more than once and other causes can be ruled out (paroxysmal) (ictal means seizure), circuitry/synaptically driven event ((propensity to seize unprovoked)

Question 16

What is the general progression graph of a seizure

Answer 16

PDS (paroxysmal depol shift) wave, with ap’s, then prolonged hyperpol (silent period), tonic then clonic phase, the post ictal depr (may have muscle weakness that mimics stroke)

Question 17

What does tonic clonic seizure involve

Answer 17

tonic- continual muscle quivering, clonic- periodic jerking (clonus=spasm)

Question 18

What is a grand mal seizure

Answer 18

involves both hemis thus loss of consciousness, generalized seizure example with motor manifestations

Question 19

Causes of seizures w homeostatic disruption

Answer 19

trauma, can take long time to appear, drug tox/withdrawals, if no prior history of trauma in adult, could be tumor/stroke
-channelopathies with alterations in v gated channels which can cause hyperexcitability etc
usu idiopathic
infection in infant etc etc

Question 20

how do you dx seizure

Answer 20

must be eeg and video recording

Question 21

do all seizures have motor component?

Answer 21

no!

Question 22

What are the two categories of seizures, and the two subcategories of each?

Answer 22

1) Generalized and 2) partial
2 types of generalized are CONVULSIVE and NON-convulsive
partial seizures can be simple and complex (focal area of brain)

Question 23

What do the types of generalized seizures involve?

Answer 23

inv entire brain
conv- have motor components, bc when stim fires easily (motor cortex sus to seizures), and non-conv- show alterations in consciousness/beh

Question 24

Ways to trigger seizures to get recording on EEG

Answer 24

hyperventilation-blow of Co2 to cause cortical hyperexcitability
photic stim- flashes of light
methohexita- short acting barb to enhance brain excit
sleep- prone to seizures in transitions between sleep and wake

Question 25

Tonic vs clonic seizure graph and sx

most common

Answer 25

tonic- lots of little quivering in graph, very dense, person is in kinda fixed position and stretched out, whereas clonic involves more alternations between quiet parts and peaks in graph, person is scrunched and jerking

Question 26

status epilepticus
def
what to do
complications
what's happening w neurons

Answer 26

• repetitive seizures w/o complete recovery in between, or seizure lasting longer than 5 min -high mort, MEDICAL EMERGENCY, can cause pulm and CV issues and DIC etc etc
• Stop seizure with anticonvulsant or anesthesia
• Both autonomic divisions activated, brains req for blood and O2 greatly increase during seizure where anoxemia is produced, need to meet demands)

Question 27

Petit mal seizures, sx etc

Answer 27

no prodromal warning, sudden onset, then go back to normal (generalized seizure), usu arise in kids at first, can be lots per day but lasting a few sec, lose consciousness during

Question 28

focal seizures sx and graph

Answer 28

activity spreads from one area to another, jacksonian progression of sx, usu start with aura, graph has FOCAL SPIKES/ SHARP WAVES and progression of sx

Question 29

What is the most common type of focal seizure?

Answer 29

Psychomotor/temporal lobe seizure:
progression of sx inv HC (susceptible region), inv alteration of csonciousness but may have normal ish behaviors that are out of context (picking at clothing, staring, complex emotional feelings), spread to other area

Question 30

Most common place for seizure to arise?

Answer 30

temporal lobe! such as HC

dont occur in cerebellum

Question 31

What is spreading depression?

Answer 31

proound depol where memb gets leaky to all ions and pumps cant keep up so ions run downhill (can recover with lots of met energy, or else irrev), nernst potls approach 0

Question 32

Migraine sx

Answer 32

start with aura but diff seizure, occip cortex aura causing vis disturbances (in seizure is usu smell), depr of EEG activity spreads (SD) from depol, vascular changes which contr to headache (lots of met energy, dilation/constr of vessels)
seq: hypoperf, aura, headache, hyperperf

Question 33

migraine stages

Answer 33

prodrome- can last hours to days, difficult conc, yawning or fatigue, light/noise sens
aura- vis illusions of lights and sparks etc, followed by blind spots, lasts up to an hr
headache- pain and light/sound sens, N/V, hours to days
postdrome- still sens, fatigue, zombie phase, hours to days